Numerous marine riser towers are known in the art, and exemplary hybrid towers and configurations are described in, for example, U.S. Pat. Nos. 6,082,391, 6,461,083, 6,837,311, 7,100,694, U.S. Pat. App. No. 2010/0172699, WO 2010/035248 and WO 2010/041229. These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
While most of the known hybrid towers can be manufactured and operated without significant challenges in offshore reservoirs at relatively shallow depth, thermal insulation, structural integrity, and weight control for hybrid towers for use at significant depth present substantial challenges. Additionally, as more reservoirs are found that produce corrosive product, solutions are needed to address the significant corrosion issues that occur within the flowlines and risers. Therefore, maintenance, repair and/or expansion of the flowlines and risers in the deepwater field developments has become increasingly important to extend the production life of the fields.
For example, to assist in the delivery of deepwater oil and gas to an offshore floating production and storage vessel (FPSO), flowline risers connect the floating vessel at the sea surface with the pipelines on the sea bed. However, such connection is not trivial, particularly where the offshore field is at a significant depth below sea level. Among other difficulties, most of the currently known structures negatively impact operational flexibility. For example, addition and/or removal, or maintenance of the flowline risers often interrupts continuous product flow. Similarly, where expansion of production capacity is desired, simple addition of new risers to existing structures is generally not possible in a cost-effective manner.
Thus, even though numerous methods and systems are known to convey gas and/or oil from a deep sea location to an offshore floating production and storage vessel or other receiving structure, various problems nevertheless remain. Consequently, there is still a need to provide configurations and methods for towers and risers.